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Re: [DNSOP] BCP on rrset ordering for round-robin? Also head's up on bind 9.12 bug (sorting rrsets by default)

Bob Harold <rharolde@umich.edu> Fri, 15 June 2018 18:38 UTC

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From: Bob Harold <rharolde@umich.edu>
Date: Fri, 15 Jun 2018 14:38:00 -0400
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To: Shumon Huque <shuque@gmail.com>
Cc: Andrew Sullivan <ajs@anvilwalrusden.com>, IETF DNSOP WG <dnsop@ietf.org>
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Subject: Re: [DNSOP] BCP on rrset ordering for round-robin? Also head's up on bind 9.12 bug (sorting rrsets by default)
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On Fri, Jun 15, 2018 at 2:28 PM Shumon Huque <shuque@gmail.com> wrote:

> On Fri, Jun 15, 2018 at 1:13 PM Andrew Sullivan <ajs@anvilwalrusden.com>
> wrote:
>
>> On Fri, Jun 15, 2018 at 11:45:19AM -0400, Erik Nygren wrote:
>> > A number of folks have been bitten by a bug in bind 9..12 where it
>> silently
>> > changes the default sorting of rrsets to always be sorted (even if the
>> > authoritative response wasn't sorted).
>>
>> I believe that RRsets are unordered sets by definition.  So I supect
>> that if people are relying on the order in which they come off the
>> wire, they're making a mistake.
>>
>
> This is all true.
>
> Yet, large numbers of application services on the Internet already rely on
> the assumption that address RRsets are returned from resolvers in a
> shuffled or randomized order for load balancing reasons. So changing this
> behavior will elicit many fierce complaints (I already observed it).
>
> --
> Shumon.
>

Round-robin is a documented feature that many applications use.  Removing
it from DNS resolvers, and then having to add it to a much larger number of
applications, does not seem like a good trade-off.

-- 
Bob Harold

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